QUndoGroup

The QUndoGroup class is a group of QUndoStack objects. More…

Synopsis

Functions

• def activeStack ()

• def addStack (stack)

• def canRedo ()

• def canUndo ()

• def createRedoAction (parent[, prefix=””])

• def createUndoAction (parent[, prefix=””])

• def isClean ()

• def redoText ()

• def removeStack (stack)

• def stacks ()

• def undoText ()

Slots

• def redo ()

• def setActiveStack (stack)

• def undo ()

Signals

• def activeStackChanged (stack)

• def canRedoChanged (canRedo)

• def canUndoChanged (canUndo)

• def cleanChanged (clean)

• def indexChanged (idx)

• def redoTextChanged (redoText)

• def undoTextChanged (undoText)

Detailed Description

For an overview of the Qt’s undo framework, see the overview.

An application often has multiple undo stacks, one for each opened document. At the same time, an application usually has one undo action and one redo action, which triggers undo or redo in the active document.

QUndoGroup is a group of QUndoStack objects, one of which may be active. It has an undo() and redo() slot, which calls undo() and redo() for the active stack. It also has the functions createUndoAction() and createRedoAction() . The actions returned by these functions behave in the same way as those returned by createUndoAction() and createRedoAction() of the active stack.

Stacks are added to a group with addStack() and removed with removeStack() . A stack is implicitly added to a group when it is created with the group as its parent QObject .

It is the programmer’s responsibility to specify which stack is active by calling setActive() , usually when the associated document window receives focus. The active stack may also be set with setActiveStack() , and is returned by activeStack() .

When a stack is added to a group using addStack() , the group does not take ownership of the stack. This means the stack has to be deleted separately from the group. When a stack is deleted, it is automatically removed from a group. A stack may belong to only one group. Adding it to another group will cause it to be removed from the previous group.

A QUndoGroup is also useful in conjunction with QUndoView . If a QUndoView is set to watch a group using setGroup() , it will update itself to display the active stack.

class PySide2.QtWidgets.QUndoGroup([parent=None])

param parent:

PySide2.QtCore.QObject

Creates an empty QUndoGroup object with parent parent .

See also

addStack()

PySide2.QtWidgets.QUndoGroup.activeStack()

Return type:

PySide2.QtWidgets.QUndoStack

Returns the active stack of this group.

If none of the stacks are active, or if the group is empty, this function returns None .

See also

setActiveStack() setActive()

PySide2.QtWidgets.QUndoGroup.activeStackChanged(stack)

Parameters:

stack – PySide2.QtWidgets.QUndoStack

PySide2.QtWidgets.QUndoGroup.addStack(stack)

Parameters:

stack – PySide2.QtWidgets.QUndoStack

Adds stack to this group. The group does not take ownership of the stack. Another way of adding a stack to a group is by specifying the group as the stack’s parent QObject in QUndoStack() . In this case, the stack is deleted when the group is deleted, in the usual manner of QObjects.

See also

removeStack() stacks() QUndoStack()

PySide2.QtWidgets.QUndoGroup.canRedo()

Return type:

bool

Returns the value of the active stack’s canRedo() .

If none of the stacks are active, or if the group is empty, this function returns false .

See also

canUndo() setActiveStack()

PySide2.QtWidgets.QUndoGroup.canRedoChanged(canRedo)

Parameters:

canRedo – bool

PySide2.QtWidgets.QUndoGroup.canUndo()

Return type:

bool

Returns the value of the active stack’s canUndo() .

If none of the stacks are active, or if the group is empty, this function returns false .

See also

canRedo() setActiveStack()

PySide2.QtWidgets.QUndoGroup.canUndoChanged(canUndo)

Parameters:

canUndo – bool

PySide2.QtWidgets.QUndoGroup.cleanChanged(clean)

Parameters:

clean – bool

PySide2.QtWidgets.QUndoGroup.createRedoAction(parent[, prefix=""])

Parameters:

• parent – PySide2.QtCore.QObject

• prefix – str

Return type:

PySide2.QtWidgets.QAction

Creates an redo QAction object with parent parent .

Triggering this action will cause a call to redo() on the active stack. The text of this action will always be the text of the command which will be redone in the next call to redo() , prefixed by prefix . If there is no command available for redo, if the group is empty or if none of the stacks are active, this action will be disabled.

If prefix is empty, the default template “Redo %1” is used instead of prefix. Before Qt 4.8, the prefix “Redo” was used by default.

See also

createUndoAction() canRedo() text()

PySide2.QtWidgets.QUndoGroup.createUndoAction(parent[, prefix=""])

Parameters:

• parent – PySide2.QtCore.QObject

• prefix – str

Return type:

PySide2.QtWidgets.QAction

Creates an undo QAction object with parent parent .

Triggering this action will cause a call to undo() on the active stack. The text of this action will always be the text of the command which will be undone in the next call to undo() , prefixed by prefix . If there is no command available for undo, if the group is empty or if none of the stacks are active, this action will be disabled.

If prefix is empty, the default template “Undo %1” is used instead of prefix. Before Qt 4.8, the prefix “Undo” was used by default.

See also

createRedoAction() canUndo() text()

PySide2.QtWidgets.QUndoGroup.indexChanged(idx)

Parameters:

idx – int

PySide2.QtWidgets.QUndoGroup.isClean()

Return type:

bool

Returns the value of the active stack’s isClean() .

If none of the stacks are active, or if the group is empty, this function returns true .

See also

setActiveStack()

PySide2.QtWidgets.QUndoGroup.redo()

Calls redo() on the active stack.

If none of the stacks are active, or if the group is empty, this function does nothing.

See also

undo() canRedo() setActiveStack()

PySide2.QtWidgets.QUndoGroup.redoText()

Return type:

str

Returns the value of the active stack’s redoText() .

If none of the stacks are active, or if the group is empty, this function returns an empty string.

See also

undoText() setActiveStack()

PySide2.QtWidgets.QUndoGroup.redoTextChanged(redoText)

Parameters:

redoText – str

PySide2.QtWidgets.QUndoGroup.removeStack(stack)

Parameters:

stack – PySide2.QtWidgets.QUndoStack

Removes stack from this group. If the stack was the active stack in the group, the active stack becomes 0.

See also

addStack() stacks() ~QUndoStack()

PySide2.QtWidgets.QUndoGroup.setActiveStack(stack)

Parameters:

stack – PySide2.QtWidgets.QUndoStack

Sets the active stack of this group to stack .

If the stack is not a member of this group, this function does nothing.

Synonymous with calling setActive() on stack .

The actions returned by createUndoAction() and createRedoAction() will now behave in the same way as those returned by stack ‘s createUndoAction() and createRedoAction() .

See also

setActive() activeStack()

PySide2.QtWidgets.QUndoGroup.stacks()

Return type:

Returns a list of stacks in this group.

See also

addStack() removeStack()

PySide2.QtWidgets.QUndoGroup.undo()

Calls undo() on the active stack.

If none of the stacks are active, or if the group is empty, this function does nothing.

See also

redo() canUndo() setActiveStack()

PySide2.QtWidgets.QUndoGroup.undoText()

Return type:

str

Returns the value of the active stack’s undoText() .

If none of the stacks are active, or if the group is empty, this function returns an empty string.

See also

redoText() setActiveStack()

PySide2.QtWidgets.QUndoGroup.undoTextChanged(undoText)

Parameters:

undoText – str